Method of manufacturing contact springs



19, 1941- J. N. REYNOLDS 2,252,899

METHOD OF MANUFACTURING CONTACT SPRINGS Filed Nov. 14, 1939 FIG.

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a v I 25 4 19 O Q INVENTOR By I JNREYNOLDS Q6. M

ATTORNEY Patented Aug 19,1941

METHOD OF.

MANUFACTURING CONTACT SPRINGS John N. Reynolds, Princeton, N. .I.,assignor to Bell Telephone Laboratories,

Incorporated,

New York, N. Y., a corporation of New York Application November 14,1939, Serial No. 304,304

2 Claims.

This invention relates .to contact springs for relays and similarswitching devices and has for its object to cheapen the cost ofmanufacturing such springs.

Relays now in extensive use are equipped with both passive or stationarysprings and active or armature operated springs made of suitable springmaterial such as nickel silver. The ends of the active springs arebifurcated and to each bifurcated portion a short bar of contact metalis welded with its linear axis extending parallel contact bars with oneof the contact bars of its mate passive spring is insured.

' In manufacturing a pair of such contact springs, the spring blanks arefirst stamped out, the four short bars of contact metal are cut to therequired length from a ribbon of the contact metal and then the fourshort bars are separately welded to the springs. It is thus apparentthat four separate welding operations are required in the manufacture ofeach pair of contact springs.

In accordance with the present invention, the manufacture of thebifurcated active spring has been simplified by first stamping out aspring blank without the bifurcating slot, thenwelding a short duplexbar of contact metal. to the end of the blank with its linear axisextending in substantial alignment with the linear axis of the blank andthen slitting the end of the blank through the depression between theduplex portions of the bar to bifurcate the blank so that one portion ofthe contact. bar will be carried .by each bifurcated portion of theblank. As an alternative construction, the ribbon from which the contactbar is cut may be wider in crosssection than the usual ribbon so thatwhen the bar is welded to the end of the spring blank and the end of theblank is bifurcated, the bar becomes severed axially to form two contactportions, each portion carried by a bifurcated portion of the blank.Since with either type of construction the crests of the contactportions are close together, separated only by the bifurcating slot, itis possible to use a single shorttransverse contact bar on the mating orpassive spring which will cooperate with both of the contact to thelinear axis of the spring. Each passive or.

portions on the active spring. This bar can therefore be welded to thepassive spring by a single welding operation. Thus in the manufacture ofa pair of mating springs, but two welding operations are necessary.

For a more comprehensive understanding of the invention reference may behad to the following detailed description taken in connection with theaccompanying drawing in which:

Fig. ,1 discloses an active or armature spring of the type now inextensive use;

Fig. 2 is an enlarged cross-sectional view of the contact ribbon fromwhich the contact bars disclosed in Fig. l are cut;

Fig. 3 is an enlarged end .view of the spring of Fig. 1 showingshortbars of contact ribbon of the type disclosed in Fig. 2, separatelywelded to the bifurcated end portions of the spring;

Fig. 4 shows a blank of an active or armature spring as stamped out inaccordance with the present invention;

Fig. 5 is an enlarged cross-sectional view of an improved duplex contactribbon manufactured in accordance with the present invention;

Fiig. 6 is an enlargedend view of the spring blank of Fig. 4 to which ashort bar of contact ribbon of the type disclosed in Fig. .5 has beenwelded;

Fig. 7 is an enlarged cross-sectional view of a modified form of contactribbon:

Fig. 8 is an enlarged end view of the spring blank of Fig. 4 to which ashort bar of contact ribbon of the type disclosed in Fig. 7 has beenwelded;

Fig. 9 shows the spring of Fig. 4'after a bar of contact ribbon of thetype shown in Fig. 5 has been welded thereto and the end of the springhas been slotted to bifurcate it;

Fig. 10 shows the spring of Fig. 4 after a bar of contact ribbon of thetype shown in Fig. 7 has been welded thereto and the end of the springhas been slotted to bifurcate it; and

Fig. 11 shows a passive or stationary spring for mating with either thespring of Fig. 9 or the spring of Fig. 10.

Heretofore in the manufacture of springs for relays or similar switchingdevices, the blanks of active or armature springs have been stamped outof spring material such as nickel silver with bifurcated contact bearingends in the form illustrated by the blank I of Fig. 1 and the blanks ofpassive or stationary springs have been stamped out of heavier springmaterial in the formdisclosed in Fig. 11. To complete an active springtwo short contact bars 2 and 3 have then been cut from a ribbon ofcontact material of the type disclosed in Fig. 2 and separately weldedto the two end portions 4 and 5 of the spring blank extending parallelto the longitudinal axis of the spring blank i. The contact ribbon from1 which the contact bars have been cut is illustrated in cross-sectionin Fig. 2 and has been fabricated by welding a strip of contact metal 8to a strip of base metal I such as nickel or a similar material and thenrolling the composite structure into a ribbon having the cross-sectionillustrated. In rolling, a rib is formed as indicated by the numeral 8on the bottom face of the ribbon to enable a better weld to be made withthe spring blank. To complete a passive spring, two short contact barssimilar to the bars 2 and 3 have been cut from the ribbon of contactmaterial and separately welded with their linear axes in alignment andextending transversely across the end of a spring blank of the typedisclosed in Fig. 11. It will thus be noted that heretofore inmanufacturing a pair of mate springs, four welding operations have beenrequired to secure the contact bars to the two spring blanks.

In accordance with the present invention, these welding operations havebeen reduced to two by the following improved construction. The blankfor the active spring is first stamped out of the spring material in theform illustrated by the blank H of Fig. 4 with a slot therein near thecontact end but with no slot extending therefrom to the end of theblank. The end of the spring blank is not therefore bifurcated. Theribbon of contact material from which the contact bar to be welded tothe spring blank is out has a cross-section illustrated in Fig. 5 orFig. 7. The ribbon disclosed in Fig. 5 is fabricated by welding twostrips l2 and [3 of contact alloy metal to a strip of base metal 14 andthen rolling the composite structure into a ribbon having thecross-section illustrated. In the rolling operation two ribs l5 and i6are formed on the base of the ribbon to enable a better weld to be madewhen a bar of the ribbon is welded to a spring blank and thelongitudinal depression I! is formed between the contact strips I2 andI3 which nearly divides the ribbon into two separate portions. Thisribbon is thus essentially a double-crested or duplex ribbon with thecontact strips on each of its crests.

As an alternative construction, the ribbon may be made similar to theribbon disclosed in Fig. 2 but with a wider contact strip l8 welded to awider base metal strip l9 and with two welding ribs and 2| asillustrated in Fig. 7.

In the further fabrication of the contact spring, a short bar may be cutfrom the ribbon of Fig. 5 and welded to the end of the blank between theslot Ill and the end of the blank with its linear axis extendingparallel to the linear axis of the spring blank H. Fig. 6 shows thecontact end of the blank after the contact bar has been welded thereto.If the contact bar is cut from the ribbon shown in Fig. 7, the end ofthe spring blank ll would appear as disclosed in Fig. 8 after the barhas been welded thereto. In either case after the welding operation hasbeen completed, the end of the spring blank is slotted at 22 by making asaw kerf or by a similar procedure along the dotted lines shown in Figs.6 and 8 whereby the slot III in the blank is extended to the end of theblank as illustrated in Figs. 9 and 10.

If a bar of double-crested or duplex ribbon is used, the saw kerf 22 ismade in alignment with the depression H as illustrated in Figs. 6 and 9and the completed spring then appears as shown in Fig. 9 with thecontact strips 12 and I3 01' the contact bar separated only by the sawkerf 22, If a bar from a ribbon of the type disclosed in Fig. 7 is used,the saw kerf divides the bar into two similar portions and the completedspring then appears as shown in Fig. 10 with the halves 23 and 24 of thecontact strip [8 separated only by the saw kerf 22.

In the fabrication of the passive spring disclosed in Fig. 11, a singlebar 25 of contact ribbon of the type disclosed in Fig. 2 is welded by asingle welding operation, transversely across the contact end of theblank 9. This bar may be short since the contact portions of the bars onthe active spring with which the passive spring is mated are closetogether as previously described.

From the foregoing it will be apparent that by the fabricationprocedures above described, the welding operations required in attachingcontact bars to a pair of mate springs have been reduced from four totwo and that as a consequence the cost of manufacture has beenmaterially reduced. Furthermore, since a single short bar of contactmaterial is welded to each passive spring, a substantial saving in thecost of precious metal contact material is also attained.

What is claimed is:

1. The method of making a bifurcated contact spring having a contact oneach bifurcated portion thereof which consists informing a ribbon withone substantially flat face and with its opposite face provided with twoparallel ridges extending longitudinally of the ribbon. welding stripsof contact metal to the crests of said ridges, cutting a short sectionfrom said ribbon to form a contact bar, welding said bar to a supportingspring with its axis positioned in substantial alignment with the axisof said spring and its fiat face in engagement with one face of saidspring and slitting the end of said spring in alignment with thedepression between the ridges of said contact bar whereby the end ofsaid spring is bifurcated and the contact bar is divided into twosections, each of which is supported on a bifurcated portion of saidspring.

2. The method of making a bifurcated contact spring having a contact oneach bifurcated por tion thereof which consists in forming a ribbon withone substantially flat face and with its opposite face provided with twoparallel ridges extending longitudinally of the ribbon, welding stripsof contact metal to the crests of said ridges, punching out a supportingspring with an axially extending slot near one end thereof, cutting ashort section from said ribbon to form a contact bar, welding said barto said spring between the end of the spring and the near end of saidslot with its axis positioned in substantial alignment with the axis ofsaid spring and its flat face in engagement with one face of said springand slitting said spring between the end thereof and said slot and inalignment with the depression between the ridges of said contact barwhereby the end of said spring is bifurcated and the contact bar isdivided into two sections each of which is supported on a bifurcatedportion of said spring.

JOHN N. REYNOLDS.

